SQL - select rows that have the same value in two columns

Question

The solution to the topic is evading me.

I have a table looking like (beyond other fields that have nothing to do with my question):

NAME,CARDNUMBER,MEMBERTY

Answer 1

If you just need to know the valuepairs of the 3 fields that are not unique then you could simply do:

SELECT   concat(NAME, "|", CARDNUMBER, "|", MEMBERTYPE) AS myIdentifier, 
         COUNT(*) AS count
FROM     myTable 
GROUP BY myIdentifier
HAVING   count > 1

This will give you all the different pairs of NAME, CARDNUMBER and MEMBERTYPE that are used more than once with a count (how many times they are duplicated). This doesnt give you back the entries, you would have to do that in a second step.